1. Field of the Invention
The present invention relates to turret machining centers, and more particularly to turret machining centers equipped with variable speed drive for the Z-axis or spindle feed direction.
2. The Prior Art
Turret machining centers are versatile machines which are adapted for boring and milling work, using a plurality of tools mounted on individual spindles spaced around the periphery of a turret. When a new tool is desired, the turret indexes to bring the desired tool into operating position, and the entire turret is adapted for vertical up-and-down movement to execute boring operations.
Because a variety of tools may be used in connection with the various spindles on the turret, it is necessary to provide some mechanism for providing for a variety of different feed speeds in the vertical direction, or, as hereinafter referred to, along the Z-axis. Although various mechanisms have been developed in the prior art for effecting a drive in the Z-axis, they have been relatively complicated and expensive to manufacture.